Brookfield previously invested in Convene, a startup that manages conference rooms and common space in office buildings. Rudin previously bought stakes in real estate tech startups Radiator Labs and Latch, according to Crunchbase. And there are many others: the Blackstone Group invested in VTS; Newmark Knight Frank and Barry Sternlicht invested in Hightower (which later merged with VTS); Jared Kushner backed Cadre and WiredScore; CBRE invested in LiquidSpace and UniKey Technologies. And the LeFrak family invested in Common, Bowery and Dealpath. I could go on and on and on.

Tech investment is so popular among real estate bigwigs in 2017 that two Los Angeles-based entrepreneurs turned it into a business model. Fifth Wall Ventures in May announced a $212 million venture capital fund focused on real estate tech. Real estate companies chipped in a little over half the money. Those commercial real estate firms are likely to be customers of the startups Fifth Wall invests in.

For startups, landing a cash infusion and a big customer in one stroke is obviously appealing. Co-founder Brad Greiwe claimed Fifth Wall regularly gets better terms in VC deals than its peers because startups are keen on selling their products to the fund’s real estate backers, which include CBRE, Prologis, Hines, Lennar, Host Hotels, Equity Residential and Macerich Properties.

Big real estate companies, meanwhile, get to invest in small startups and all but ensure that their investment increases in value by becoming a major customer and pushing up the startup’s revenues. Fifth Wall’s other co-founder Brendan Wallace calls this “the ability to influence outcomes for early-stage companies.” If that sounds a little like cornering the market, it’s because it kinda is.

“If I’m an investor in one of those companies I’m thrilled, because that’s moat,” said Talia Goldberg of Bessemer Venture Partners.

Real estate firms that double as VC investors have helped startups grow. But years from now that moat could become an obstacle to innovation.

If all goes according to plan, firms like VTS or Opendoor will keep on growing and become big, billion-dollar businesses. Eventually, a new crop of startups are likely to pop up, offering better technology and challenging the incumbents. Will real estate companies that hold stakes in the incumbents listen to their pitch? After all, ditching a company they invested in might cost them serious money.

Keep in mind that it’s hard enough to challenge established tech firms as it is. When commercial property database CoStar launched in the 1980s, it was a major innovator. But over the years its business model became stale and in recent years a couple of startups, including CompStak and RealMassive, challenged its dominance in the data market. They face daunting odds. CoStar has an unrivaled trove of data and the network effects that go along. It has plenty of money, which allowed it to clobber smaller competitors with endless copyright infringement lawsuits. Now imagine that, on top of all that, CBRE and Cushman & Wakefield owned stakes in CoStar. Its rivals wouldn’t stand a chance.

Rudin Ventures’ Michael Rudin doesn’t see his tech investments as a potential obstacle to innovation. He thinks that firms like Honest Buildings will keep innovating to stay competitive. “If not, for whatever reason: at the end of the day it’s about business. If it’s better for our business to use a different technology, we’ll look at that,” he said.

And according to Goldberg, incumbents already enjoy a big advantage because adopting new technologies can be disruptive, which makes real estate companies reluctant to ditch what they have. Whether or not they also own a stake in their vendor doesn’t make that much of a difference, she argued.

“Innovation isn’t marginal,” he argued — it happens in big leaps and when they occur, firms like Brookfield or Blackstone will have no choice but to adopt game-changing technologies if they want to stay competitive.

Then again, think of the cellphone industry over the past decade. The iPhone was a game changer. Since then, advances in the industry have arguably been minor — an improved camera here, a waterproof screen there, each small advance due to one company forcing the others to catch up. But the cumulative effect of all these little innovations was huge: the iPhone you can buy today is worlds better than the 2007 model.

Suppress enough of those tiny advances, and you stifle major innovation. The same goes for commercial real estate tech.

I’m not arguing real estate companies should stop investing in startups. On the contrary, tech firms need every boost they can get if we want the real estate industry to escape the stone age.

But firms like Brookfield, Rudin and Blackstone should ensure that the executives who procure technologies aren’t the same people that invest in startups and that the latter don’t influence the former. Otherwise, they may end up helping startups today at the cost of stifling innovation tomorrow.

Correction: CBRE did not invest in Yardi, as an earlier version of this post erroneously reported.